Plug-in type connectors are known which permit connecting electrical conductors, or a plurality of electrical conductors, with respective other electrical conductors through an electrically conducting coupling. Further, it is known to connect optical conductors with each other to provide a light transmission from one optical conductor to another optical conductor. However, there is a problem in providing a sufficient mechanical stability and protection for the conductors, especially when using optical conductors, such as glass fiber cables. More specifically, it is difficult to protect these optical conductors inside the connector. Such protection must be assured, especially when the connectors are used for equipment that is subject to security requirements, such as computers, one-way and two-way communication equipment, devices in the aircraft technology, and in computer controlled machinery. In connection with optical conductors it has been found that even small tension loads to which the optical conductor may be exposed lead, if the exposure is prolonged, to micro-cracks which are likely to cause a complete break of the optical fiber conductor in due course.
Optical fibers have a bending angle which relates to a limit angle that assures a total reflection of light impinging on the optical conductor. If a bend in the optical conductor exceeds the limit angle, light will exit from the light conductor sidewalls, rather than at its end. Light exiting through the side walls of the optical conductor is lost and leads to a reduction in the transmitted light which reduces the light intensity and thus increases the damping. The above mentioned tension loads should be avoided, since they tend to damage the light conductor. However, the bending of the light conductor and the resulting bending stress, as well as torsion loads, causing torsion stress, are also disadvantageous and must be avoided as much as possible.
In spite of the above mechanical problems, optical conductors have rapidly found wide-spread acceptance in data transmissions due to the high data transmission rates of which optical conductors are capable for many uses or purposes. By combining at least one optical conductor with at least one electrical conductor, it has become possible to provide a special cable construction which, to some extent, avoids the above disadvantages of the use of optical conductors by protecting the optical conductor with the electrical conductor which encloses the optical conductor substantially coaxially. However, coupling devices for interconnecting sections of such cables are not available for providing a simple, yet reliable connection between such cable sections.